The invention relates to a method for packaging flat articles. The invention relates also to a packaging apparatus.
Upon packaging large series of flat articles, they are formed into stacks of suitable size which are moved into the package. In these stacks, the articles are parallel, and the aim is to place them tightly against each other in the direction transverse to their planes. A typical example of articles of this kind is envelopes. The handling and packaging of envelopes is described e.g. in the Finnish Patent No. 94042 and in the Finnish published specification No. 97355 by the applicant.
Some articles have such a structure that the thickness of the article is not constant in the direction of its plane. A good example of such a product is envelopes and bag covers which are filled in from the short end, at which there is a closing flap and possibly also a paper covering the adhesive area on it, whereby the product is clearly thicker at one end. If the closing flap is folded out, it forms the thinnest end of the article. When articles of this kind are packaged with an automatic packaging apparatus, in which the articles run in a continuous stack, such constructional features cause more thickness at one end of the stack, which may hamper space utilisation.
The purpose of the invention is to present an improvement to the above-mentioned prior art. From the continuous stack entering the handling step, the product batch to be packaged is not separated and moved as such into the package, but stack portions smaller than the product batch are separated from it and placed next to each other so that the second stack portions come into a 180xc2x0 rotated position in relation to the first ones, and the adjacent stack portions so handled constitute the product batch, in which the thicker ends point at opposite directions.
The apparatus of the invention, in turn, is characterized in what will be presented in the characterizing part of the appended claim 7. The apparatus comprises means for separating a stack portion from the continuous stack, a gripper which is suspended in a rotation axle and which effects a rotation of 180xc2x0 of the stack portions in relation to each other, as well as a product batch forming device in the area of motion of the gripper for arranging the stack portions next to each other.
In respect of the other advantageous embodiments of the invention, reference is made to the dependent claims and the description herein below.